On outcrops, quartz diorite of the Amarault Pluton is very homogeneous. In altered surface, it is characterized by a typical black and white mottled appearance caused by the arrangement of grains that form clusters of ferromagnesian and quartzofeldspathic minerals. Some intrusions of granular enderbite are observed, as well as rare decimetric to metric paragneiss enclaves. Quartz diorite contains 8-15% quartz, up to 7% K-feldspar and 20-30% ferromagnesian minerals consisting of green hornblende and brown biotite in roughly equal proportions. Relics of orthopyroxene variably transformed into iddingsite as well as clinopyroxene in the core of hornblende crystals were also observed in several places. The rock is massive in appearance, but may contain slight foliation defined by the alignment of ferromagnesian minerals. In thin sections, quartz diorite displays well-preserved magmatic textures and low recrystallization indicated by the presence of plagioclase subgrain clusters. There are also myrmekitic textures associated with small interstitial K-feldspar grains. Apatite, opaque minerals and zircon are present in minor amounts.